1. Technical Field
The present invention relates to data processing systems and, in particular, to storage systems. Still more particularly, the present invention provides a method, apparatus, and program for teaming storage controllers.
2. Description of the Related Art
Redundant Array of Independent Disks (RAID) is a disk subsystem that is used to increase performance and provide fault tolerance. RAID is a set of two or more ordinary hard disks and a specialized disk controller that contains the RAID functionality. RAID improves performance by disk striping, which interleaves bytes or groups of bytes across multiple drives, so more than one disk is reading and writing simultaneously. Fault tolerance is achieved by mirroring or parity. A failed drive can be hot swapped with a new one, and the RAID controller automatically rebuilds the failed drive's data.
RAID systems come in all sizes from desktop units to floor-standing models. Some implementations include a plurality of RAID storage controllers, each accessing a set of disks. Several physical disks may form a logical drive or volume. However, sets of physical drives are connected to respective controllers. If a controller fails, the physical drives, as well as the corresponding logical drives, become inaccessible.
Therefore, it would be advantageous to provide an improved mechanism for providing fault tolerance between storage controllers.